Shortly after he had moved to London he had been asked to investigate astringent plants in connection with tanning. To this end he visited tan-yards and farmers, and in 1802 began to deliver a course of lectures on “The Connection of Chemistry with Vegetable Physiology.” These lectures proved remarkably popular, and for ten years he repeated them at the meetings of the Board of Agriculture. They were later published in book form, and so great was their interest that they were translated into almost every European language. _The Edinburgh Review_, that dean of British critics, said, “We feel grateful for his having thus suspended for a time the labors of original investigation, in order to apply the principles and discoveries of his favorite science to the illustration and improvement of an art which, above all others, ministers to the wants and comforts of man.” When his agricultural researches were finished he went back to his studies with the voltaic pile or battery. He discovered that potash and soda can be decomposed, with the resultant metals of potassium and sodium. When he made this discovery he was so delighted that he danced about the room, and was too excited to finish the experiment for some time. He had worked too hard, and soon after this discovery he fell ill. For days all London watched for the bulletins of the young chemist’s condition. Fortunately he recovered, and in time went back to the work which was proving so invaluable for the world of science. The Royal Institution now provided him with a voltaic battery that was four times as powerful as any that had previously been constructed. With this he made numberless chemical discoveries. The Royal Society had made him a fellow when he was twenty-five years old, and one of its secretaries when he was twenty-nine. His London lectures grew continually more popular. The Dublin Society invited him to lecture in that city, and his course at once attracted the greatest attention. He was already the scientific lion of England, but withal a very modest and unassuming lion. Cuvier said, “Davy, not yet thirty-two, in the opinion of all who could judge of such labors, held the first rank among the chemists of this or of any other age.” The National Institute of France awarded him the prize that had been established by Napoleon for the greatest discovery made by means of galvanism. Then, in 1812, when he was thirty-three, he was knighted by the Prince Regent.